Polarized outlet section for electric wiring systems



POLARIZED OUTLET SECTION FOR ELECTRIC WIRING SYSTEMS June 20, 1944.

` Filed April 27, 1942 INVEN'IroR. Joseph F O Braen Z. /\c dat?. HATTORNEY Patented .une 20, 1944 POLARIZED OUTLET SECTION Fon ELECTRICWIRING SYSTEMS Joseph F. OBrien, Jersey City, N. J., assignor to John B.Pierce Foundation, New York, N. Y., a

corporationof New York Application April 27, 1942, Serial No. 449,608

6 Claims.

This invention relates to electric wiring devices, and particularly, toa polarized outlet section providing means for efficiently and safelygrounding wiring systems and the exposed metal parts of electricalequipment connected thereto.

This invention is particularly applicable for use withmulti-conductorwiring systems and conductor units therefor, such Yas aredescribed and claimed in my presently co-pending application Serial No.398,030, entitled Electricity conductor units with conductor-sizeadjustment.

In such systems, conductor-,containing units, comprising a plurality ofelectricity conductors Supported within a `non-conductive housing ininsulated spaced' relationship, are mechanically and electricallyinterconnected in seriatim to form a circuit of any desired length, withoutlet facilities as required.

Conductor units of the type aforesaid eliminate the need for providingground paths for fault currents which may occur in metallic enclosures,such as B-X cable, metallic bus duct or the like. Where groundedpolarized circuits are employed, it is considered the best engineeringpractice to provide a positive path for fault currents, in the form of adefinite low resistance bond between current carrying parts ofelectrical accessories which might'be accidentally touched or contactedby persons, andthe neutral orv grounded wire of the circuit. Thegrounding of exposed metal parts of equipment which contain live circuitconductors prevents the occurrence of a potential above ground, onjsuchexposed metal parts. With respect to electric circuits per se, thepurpose of grounding such a circuit is forlimiting a rise in potentialabove that for which the insulation is designed; or to limit the maximumpotential to ground due to normal operating conditions.

By adequately' bonding the exposed metal parts of electrical accessoryequipment to the neutral, ine., grounded, conductor of the circuitsupplying such equipment, an assured path to ground for fault currentsoccurring in exposed metal parts of each piece' off electrical accessoryequipment is provided; an added advantage is that failureof the path to'ground causes an interruption of the circuit, and such a failure isimmediately indicatedV by cessation of performance'ofthe electricalaccessory equipment served by the circuit.

Anobject of the invention, therefore, is to provide a polarized outletsection for an electric wir.. ing system ofthe typeaforesaid, havingimproved means for groundirlg'the circuit,,and electric accessoryequipment usedtherewitn' An object of the invention is to provide apolarized outlet section containing provisions for providing adequateprotective grounding on a two Wire circuit.

An object of the invention is to provide an outlet unit for a three wire115/230 volt circuit wherein the loads on such a circuit may bebalanced, yet adequately and safely grounded.

An object of the present invention is to provide an improved electricaloutlet wherein variant grounding and circuit arrangements may beobtained with a minimum of parts, thereby simplifying the manufactureand stocking of conductors, contacts, and housing elements.

Other features and advantages will hereinafter appear.

In the accompanying drawing:

Fig. 1 Vis a plan view of a portion of a wiring system containing apolarized outlet section embodying the present invention;

Fig. 2 is a vertical section taken on lines 2-2 of Fig. 1;

Fig. 3 is a bottom plan view of the cap member of the improved polarizedoutlet section;

Fig. 4 is a plan section taken on lines 4 4 of Fig. 2 showing one formof grounding circuit;

Fig. 5 is an elevation of the unitary conductor assembly for the outletSection;

Fig. 6 is a plan view of the unitary conductor assembly showing anoptional grounding circuit;

Fig. '7 is another plan View o-f the unitary conductor assembly, showinga third method of providing for ground connection;

Fig. 8 is an end View of the unit; and

Fig. 9 is a vertical section, taken on lines 9 9 of Fig. Il.

Referring to the drawing for a more detailed description of theinvention, the improved polarized outlet unit IU is shown aselectrically and mechanically interconnected with wiring units Il, Il,said units preferably being of the three conductor type described andclaimed in my said co-pending application Serial No. 398,030.

Such three conductor units may be connected to the power source toprovide a hot wire, a neutral wire, and a ground wire, in which theneutral and ground conductors may be bonded to a common ground; or alili/230 volt circuit wherein the conductors are arranged in se quenceas a hot wire, a combined neutral and ground wire, and a Second hetwire. Optionally, one of the conductors ymay be removed, to provide atwo wire circuit comprising a hot wire" and a combined neutral andground wire.

heavy rigid wires.

rindependently o-f the positions of The outlet unit forming the presentinvention may be employed with any of the above wiring systems toprovide means whereby full and complete ground protection is Vaffordedany electrical accessory, such as an electric drill or the like, whereinmetal portions which are grasped or contacted by the operator mayaccidentally be crossed with a hot wire of the circuit.

The unit I is basically of a three wire type. A cap I2 is provided withthree apertures I3 arranged in conformity with the positioning ofcontact blades of standardized three wire attachment plugs. End wallsI4, I5, and I5a of such cap have a plurality of registering notches I6to receive and position electricity conductors, as later described.Additionally, the cap I2 has a central body formation I'I vwhereinpockets register with the apertures I3. Such pockets form individualhousings for the contact clips Il, see Fig. 2.

Cap I2 is substantially hollow, and is closed byra base member 20, whichfits internally thereof. As shown in Fig. 2, the ends of the housing areof male and Ifemale configuration to form broken joint interconnectionwith adjacent units I I. A

The base 29 is substantially planar, except for grooves 2|, 2I, ZI, atthe ends thereof to coop crates with the grooves I6 in the cap member toform angular channels for the securement` and Q uniform positioning ofelectricity conductorsl and upstanding wall formations 22, 22, whichintert, seeFig. 8, with suitable grooves in the end walls of the cap I2.Centrally of the base 20, see

Fig. 9, is a pair o-f relatively low walls 23, which 5..

electrically isolate portions of the conductors, as later described.Positioned upon the base isa unitary conductor organization comprising aplurality-illustratively three, in conformity with the basic threeconductor wiring system-of electricity conductors 24 having flattenedportions intermediate their ends; the conductors are secured to theunderside of a plate 25 of insulating material, said plate beingdimensioned to t snugly between the side walls of the cap I2, as shownin Fig. 9. The flattened portions of the conductors 24 t between thewalls 23 of the base 2l), said walls effectively mutually insulating theconductors.

The conductors 24 are desirably of rods or One end, 24a, 'of eachconductor is provided with a tapered or rounded end, and the oppositeend is tted with a split sleeve 26, of phosphor bronze or similar springmaterial having good conductivity. The sleeves 26 may be soldered orotherwise suitably secured to the conductors.

As shown in Fig. 2, the male end 24a of a conductor nts within a tubularconductor 2l o-f unit II, with a tight frictional engagement affordingproper electricity conduction. At the opposite end, the sleeve 25provides a springable socket into which the tapered end of a conductor2'! of the next succeeding unit II fits snugly.

The electric contact clips I3 are standardized, and electricallyinterconnected to the appropriate electricity conductors 24 by suitablebus bars I8', to which the clips are individually connected, and which,in turn, are connected to the conductors 24. Bus bars I 3 rest upon theface of insulating block 25 remote from the conductors 24, and may vbesuitably positioned on said block such conductors 24. A

It is obvious. therefore, that the electricity conductor unit,comprising the respective conductors, the insulating block, and thecontact clips, is a readily removable unit, and a conductor unit havingvariant grounding characteristics may be used with a standardized capand base member. This facilitates stocking and selection of the unitsI0, because once the type of grounding circuit is decided upon, theappropriate conductor element may be used with the standardized cap andbase member.

Figs, 4 and 6, taken together, represent units alording adequate groundprotection, with .balanced loads, in a /230 volt, three wire system. Thecenter conductor of each of these outlet units is marked NG,representing combined neutral and ground. In a three wire 115/230 voltsystem using the circuit arrangement of Fig. 4, therefore, two 4of thecontacts I8 are electrically connected with the NG conductor, and thethird is connected to hot wire B. In this manner, a three wireConnection plug may be employed for apparatus requiring 115 volts; theground path from the apparatus is through the combined neutral andground conductor of the circuit,` to which the third, or grounding, poleof the three pole plug, is connected.

In Fig. 6, a similar arrangement is provided, but hot Wire A and neutralconductor NG form the current supply of conductors, and neutralconductor NG serves as the common grounding conductor.

In a 115/230 volt, three wire circuit,`therefore, a unit embodying theFig. 4 circuit and a similar section embodying the Fig. 6 circuit may beused consecutively, thereby balancing the load, because electricalaccessories connected to such outlet sections will draw current from theA--NG conductors and from the B-NG conductors, while maintainingadequate ground connections for the respective pieces of apparatus.

`This circuit arrangement has an additional advantage, namely, that solong as current is supplied to the apparatus, the ground connection mustnecessarily be secure, for if the grounding circuit were broken, thecurrent flow would necessarily be interrupted,

Either the Fig. 4 or the Fig. 6 arrangement may be employed as a twowire, grounded, unit by eliminating conductor A from the Fig. 4organization or conductor B from the Fig. 6 circuit. In sucharrangement, the conductor NG serves to provide protective grounding ina two Wire circuit. Such arrangement is known as a common ground. Fig. 7showsa three wire circuit in which the neutral conductor N and theground conductor G are individual circuits, bonded together to a commonground at some convenient point in the wiring circuit.

By positioning the conductors of the unitary conductor organization onthe underside of insulating block 25 and the Contact clips I8 on theopposite side thereof, the various grounding cirz .,cuits may beeffected with' but four forms or 'swung into' position over` an adjacentconductor '25, special insulationme'ans., would berequired t'o protectthe" bus bars I8V; against short circuit with' conductorsofoppovsitepolarity.A

Reduction in number and simplification of the bus bars I 8 required forachieving the variant grounding circuits effects substantial economiesin manufacture and simplifies stocking and warehousing,

Whereas I have described my invention by reference to specic formsthereof, it will be understood that many changes and modifications maybe made provided they do not depart from the scope of the claims.

I claim:

l. A polarized outlet section for an electric wiring system, comprisinga substantially hollow cap member of insulation material formed with aplurality of apertures in an outer face to individually receive a bladeof a polarized attachment plug, said cap member having a plurality oftransverse Walls provided with mutually registering notches, a basemember of insulation material cooperating with said cap member to forman enclosure therefor, said base member having amatching plurality ofnotches for registry with the notches in said cap member to formlongitudinally-extending passages, and unitary conductor means forremovable positioning Within said housing upon said base, said unitaryconductor means including a plate of insulation material, a plurality ofelectricity conductors positioned in parallel relationship beneath saidplate and secured thereto, and electric contact means equal in number tothe blades of such polarized attachment plug positioned on theinsulating plate and individually electrically connected to selectedelectricity conductors; the conductors of said unitary conductor meansbeing coextensive with the cap member and individually confined withinsaid passages for maintenance in mutually spaced, insulated,relationship.

2. A polarized outlet section for an electric wiring system. comprisinga substantially hollow cap member formed with a plurality of aperturesto individually receive a blade of a polarized attachment plug, a basemember associated with said cap member to enclose the same, and unitaryconductor means for removable positioning within said housing, saidconductor means including a plate of insulation material, a pluralitywiring system, comprising a substantially hollow cap member, a removablebase member therefor, and a unitary conductor means adapted to beremovably positioned upon said base for snug confinement within saidhousing, said unitary conductor means including a plate of insulationmaterial, a plurality of naked conductors secured to the underside ofsaid plate in mutually insulated, spaced relationship, and electriccontact means` disposed on the upper side of said plate and electricallyconnected to certain of said conductors; said base member having groovesto individually receive the electricity conductors.

4. A polarized outlet section according to claim 2, wherein the plate ofinsulation material is dimensioned to fit snugly between side Walls ofthe cap member.

5. A polarized outlet section according to claim 2, wherein theelectricity conductors of said unitary conductor means are flattenedintermediate their ends to provide a base for the stable securement ofsaid plate of insulation material.

6. An outlet unit for an electric wiring system comprising a housingconsisting of a substantially hollow cap section having plug-bladeapertures and a removable base plate, and a conductor unit for removablepositioning within said housing, said conductor unit comprising a plateof insulation material, a plurality of electricity conductors securedthereto in spaced relationship, said conductors being of such length asto present terminals at the ends of said housing for connection toconductors of the wiring system, and electric contact means disposed onthe side of the insulation plate opposite the electricity conductors forregistry with apertures in said cap section to receive the blades of anelectric attachment plug.

JOSEPH F. OBRIEN.

